Fresh fish foods made of internal organs such as the guts of fish have been, available on the market. However, the freshness of fish decreases immediately after its death. In particular, the internal organs of fish start to drip or to be deformed in several hours after its death. Such a phenomenon is considered to be caused by miscellaneous germs originally kept in the fish body. Although the propagation of the germs is inhibited by the resistance of the fish itself to germs while the fish is alive, the resistance is lost and the germs start to propagate after the death of the fish. It is considered that various kinds of miscellaneous germs are present in the internal organs of fish. After the internal organs have rotted, the membranes covering them are broken and other organs also start to rot.
Therefore, when a fresh product is to be produced from, for example, guts of fish, as fresh as possible, fish must be obtained and the guts must be taken out of them as soon as possible. However, although the rotting velocity of the internal organs varies depending on the kind of the fish, in fact, the rotting velocity of the internal organs is generally high even when the fish is fresh. Thus, the amount of the utilizable guts is limited.
Further, the rotting proceeds also in the ovary or milt adjacent to the internal organs. In fish, the ovary or milt is separated from the internal organs only by an extremely thin film (or membrane) and, therefore, the miscellaneous germs easily invade into the ovary or milt also from the internal organs. Under these conditions, fresh fish immediately after the catch is required for obtaining fresh ovary or milt. The ovaries to be eaten include, for example, roes of salmons and trouts (Sujiko) and also those roes wherein eggs are separated from each other (Ikura). The milts to be eaten are available under the name of soft roe.
The object of the present invention is to provide a process for treating fresh fish for producing fresh products having an elongated period of tasting time or an increased commercial value from the internal organs of fish, as well as fresh products from adnexa such as ovaries and milts.